An embodiment of present invention relates to the field of digital computer systems, and more specifically, to a method for enforcing constraints on data in a data processing system.
Database management systems (DBMS) typically offer the possibility to define constraints on the database schema to which the managed data must adhere. It is the responsibility of the DBMS to enforce the defined constraints. Whenever it executes a data manipulation statement, it must check whether the constraints are still met after the change. If the constraints are not met, then the DBMS must reject the statement. For example, unique and referential constraints are not cheap to evaluate, as they must search an entire table for the existence of duplicate values or the referenced key, respectively. Thus there is need to improve the performance of such systems for evaluating the constraints.